Migrate OAuth callback to Spring configuration property

Signed-off-by: Tomas Slusny <slusnucky@gmail.com>

http-service/src/test/resources/application-dev.yaml

@@ -25,3 +25,7 @@ datasource:
     url: jdbc:mysql://localhost:3306/runelite-tracker
     username: runelite
     password: runelite
+
+# Development oauth callback (without proxy)
+oauth:
+  callback: http://localhost:8080/account/callback